This error appears when the Gemini drive senses an AC input voltage that exceeds the allowable voltage range (212VDC for the GV-L3, 410VDC for all other power ranges). An over-voltage fault can be caused by a voltage spike in the AC supply, or by back-driving the motor.
"Back-driving," also known as "regeneration," means that the motor is being powered to move in one direction, but is moving the opposite direction. Or, the motor is being turned and not under power at all. In these cases, the motor is now a generator rather than a motor.
There are two main scenarios for "back-driving" a motor:
1) A vertical load falling down (i.e. the motor is under-powered or has no power at all).
2) A horizontal move with a large inertial load that is being aggressively decelerated and cannot stop the load as intended. This is rather like a car skidding to a stop.
1) Unless the drive has sustained permanent physical damage due to the high level of voltage that initially caused the fault, typing a RESET command or cycling AC power to the drive will clear this error bit.
2) Take precautions to prevent excessive input voltage spikes from reaching the drive by incorporating either a surge protector or AC line filter between the AC power source and the Gemini unit.
3) Check to make sure that the motor load is not back-driving the motor, as this will cause voltage to flow back into the drive from the motor. This can destroy the circuitry within the drive.
TEST TO MEASURE THE HIGH-VOLTAGE TRIP POINT:
Put a variable high-voltage power supply directly to the VBUS + and -.
Turn it up to about 90VDC and the drive will power up.
Connect a resolver (or encoder) and then enable the drive.
Turn up the voltage until the drive disables due to TASX.12.
MEASUREMENT TO SEE THE HIGH-VOLTAGE OCCUR:
Connect an oscilloscope to the VBUS+ and - connections. This shows the bus voltage which is the AC power rectified plus any voltage generated by the motor if it is being back-driven.